Maintenance/Test Circuit Pack (Tn771D) - Avaya MCC1 Maintenance Procedures

Packet and serial bus maintenance
S8100 packet bus fault isolation and repair
2 If the Packet Bus problem still exists, port circuit packs (those in the purple slots) are removed to
look for circuit pack(s) that have failed and/or have damaged the Packet Bus pins (a diagram of
the backplane pins is provided later).
3 If the Packet Bus problem is still not resolved, the same procedure is attempted for the control
complex circuit packs.
4 If the problem is still not resolved, or if the Packet Bus faults are known to have open leads, a
procedure is undertaken in which the bus terminators and cables are replaced. If this does not
resolve the problem, the carrier connectivity of the port network is reconfigured to attempt to
isolate a faulty carrier.

Maintenance/Test circuit pack (TN771D)

Packet bus reconfiguration is available only in high and critical reliability systems. In such systems that
use the packet bus, a Maintenance/Test is required in each port network. In other configurations (for
example, Standard Systems, no packet bus use), the circuit pack is optional.
CAUTION:
All TN771 circuit packs must be of TN771D vintage or later.
Normal packet functionality
The Maintenance/Test Packet Bus Port provides the packet bus testing and reconfiguration capabilities.
When the port is in service, the port continuously monitors the packet bus for faults (or recovery from
faults), and it reports this information to packet bus maintenance.
The yellow LED on the TN771D Maintenance/Test circuit pack provides a visual indication of the state
of the packet bus, as follows:
• Blinking at a rate of 1 per sec — the Maintenance/Test Packet Bus port cannot swap leads to
correct a Packet Bus fault (that is, there are too many faults). The Packet Bus may be
unusable. If the failures detected by the Maintenance/Test Packet Bus port are open lead
failures, the Packet Bus may still be operating.
On steady — the Maintenance/Test Packet Bus port has swapped leads on the Packet Bus. The
•
Packet Bus is still operating.
NOTE:
Because the yellow LED on the Maintenance/Test circuit pack can also be on steady when
the other ports on the circuit pack are in use, the ports on the Maintenance/Test circuit
pack used for ISDN-PRI trunk testing must be busied out before the Maintenance/Test
circuit pack is used to help resolve Packet Bus faults. This is done via the busyout port
PCSS02 and busyout port PCSS03 commands. Also, be sure to release these ports
when the process is completed.
Off — there is no Packet Bus fault present.
•
NOTE:
It takes 5 to 10 seconds for the LED to respond to a change in the state of the Packet Bus.
252 Maintenance Procedures
December 2003